1. Field of the Invention
This invention relates to a method for constructing an island in an ice-covered body of water using the natural sheet of ice as an integral part of the island.
2. Description of the Prior Art
In shallow water polar regions, which are covered with a sheet of ice at least a part of the year, man-made islands have proven to be an advantageous structure to use as a base for oil-field operations. Such man-made islands have been used as bases for exploratory oil well drilling operations and will be used as well for oil production related operations. To survive the harsh environmental conditions of the arctic, these islands must be protected against erosion and overtopping by waves and storm tides during the summer and, during the winter, they must be able to withstand significant lateral loads exerted by movement of the surrounding sheet of ice.
Islands constructed in shallow water regions off the northern coast of Canada have been built entirely of fill material, such as gravel and silt. Most of those islands were built during the summer while there was no ice cover. At least one was built in winter by removing a section of the sheet of ice which had formed on the body of water and dumping fill material directly on the bottom. These all-fill-material islands have certain limitations. In certain polar regions, a sufficient quantity of fill material is not readily available and must be transported great distances to the island construction site. Moving the vast amount of fill material needed to construct an island great distances in the arctic is very expensive. Even when fill material is available near the island construction site, dredging or mining operations in the arctic are expensive.